The invention relates to a method and arrangement for the method for the analog-to-digital conversion of an analog signal, particularly a picture signal, into a digital signal by means of at least two analog-to-digital converters which are clocked in a phase-shifted manner and whose output signals are combined to a digital signal.
Such a method is known from DE-OS 35 43 744 and in said method an analog signal is applied to a plurality of analog-to-digital converters arranged in parallel. The output signals of the analog-to-digital converters are time-interleaved and are available as the output signal. This output signal can have a clock frequency which is n times as high as the sampling frequency of the individual analog-to-digital converters in the case that n analog-to-digital converters are used.
The principal drawback of this method is that in practice the analog-to-digital converters and analog prefilters have different characteristics and different sensitivities. In the output signal, which includes the time-interleaved output signals of the analog-to-digital converters, this gives rise to an inaccuracy which fluctuates in time. For example, even in the case of a constant input signal the output signal can thus have values which fluctuate in time. In addition, it is possible that output signals appear which differ in a quasi-dependent manner on the instant at which the input signal is sampled and, consequently, on the analog-to-digital converter by means of which the signal is sampled. Thus, in this method the sensitivity and/or the characteristic of the circuit and, consequently, the values of the digital output signal change depending on the analog-to-digital converter by which the input signal is being sampled. This is undesirable.
It is an object of the invention to provide a method and an arrangement which mitigate these problems.